The Cabinet of Dr. Caligari (1919)

Dr. Caligari is a hypnotist (Werner Krauss) who travels with a carnival and a somnambulist named Cesare (Conrad Veidt). When the friend of a man called Francis (Friedrich Feher) is killed in a German village, he suspects Caligari, and eventually discovers that the somnambulist is committing the murders under Caligari's orders.

Trivia: Considered one of the greatest horror movies of all time, The Cabinet of Dr. Caligari is a masterpiece of silent film and a landmark of the German Expressionist style.